Field of the Invention
The present invention relates to agricultural balers, and, more particularly, to systems for powering such balers.
Description of the Related Art
Agricultural harvesting machines, such as balers, are used to consolidate and package crop material so as to facilitate the storage and handling of the crop material for later use. In the case of hay, a mower-conditioner is typically used to cut and condition the crop material for windrow drying in the sun. In the case of straw, an agricultural combine discharges non-grain crop material from the rear of the combine defining the straw (such as wheat or oat straw) which is to be picked up by the baler. The cut crop material is typically raked and dried, and a baler, such as a large square baler or round baler, straddles the windrows and travels along the windrows to pick up the crop material and form it into bales.
On a large square baler, a pickup unit at the front of the baler gathers the cut and windrowed crop material from the ground. The pickup unit includes a pickup roll, and optionally may include other components such as side shields, stub augers, wind guard, etc.
A packer unit is used to move the crop material from the pickup unit to a duct or pre-compression chamber. The packer unit forms a wad of crop within the pre-compression chamber which is then transferred to a main bale chamber. (For purposes of discussion, the charge of crop material within the pre-compression chamber will be termed a “wad”, and the charge of crop material after being compressed within the main bale chamber will be termed a “flake”). Typically such a packer unit includes packer tines or forks to move the crop material from the pickup unit into the pre-compression chamber. Instead of a packer unit it is also known to use a rotor cutter unit which chops the crop material into smaller pieces.
A stuffer unit transfers the wad of crop material in charges from the pre-compression chamber to the main bale chamber. Typically such a stuffer unit includes stuffer forks which are used to move the wad of crop material from the pre-compression chamber to the main bale chamber, in sequence with the reciprocating action of a plunger within the main bale chamber.
In the main bale chamber, the plunger compresses the wad of crop material into flakes to form a bale and, at the same time, gradually advances the bale toward the outlet of the bale chamber. The plunger reciprocates, back and forth, toward and away from the discharge end of the baler. The plunger may include a number of rollers which extend laterally outward from the sides of the plunger. The rollers on each side of the plunger are received within a respective plunger slot formed in the side walls of the bale chamber, with the plunger slots guiding the plunger during the reciprocating movements.
When enough flakes have been added and the bale reaches a full (or other predetermined) size, a number of knotters are actuated which wrap and tie twine, cord or the like around the bale while it is still in the main bale chamber. The twine is cut and the formed baled is ejected out the back of the baler as a new bale is formed.
During a compression cycle of the plunger as described above, the plunger moves through a compression stroke as it advances into the main bale chamber, with the highest load on the plunger occurring at the end of each compression stroke. As balers become increasingly larger, the peak loads on the plunger during compression strokes likewise become increasingly larger. One way to compensate for these higher peak loads is to use a larger flywheel coupled with a gearbox which drives the plunger. As the plunger reaches the end of the compression stroke, the momentum of the heavier flywheel helps carry the plunger through the peak load at the end of the compression stroke. If the flywheel is not heavy enough then high loads are transferred back through the driveline to the base unit, which can result in lugging down of the engine onboard the base unit. However, a flywheel which is too large is also undesirable since it typically requires a traction unit with a larger horsepower (HP) rating to start and drive the flywheel forming part of the driveline of the baler. It would be desirable to use a smaller traction unit regardless of the size of the flywheel.
US 2010/0108413 describes a baler having a jog drive system drivingly connected within the primary drive system. This jog drive system serves as a source of power to the various performance systems in the baler when movement of components within the baler is required for maintenance or adjustment. The jog drive system comprises a jog motor which can be in the form of a hydraulic motor, an electric motor or other suitable drive mechanism for slowly rotating the flywheel of the baler and thereby advancing all performance systems. The jog motor can be connected to a hydraulic system of the tractor, to an electric system of the tractor or can be provided with other sources of power input. This jog drive system is foreseen to assist the operator by supplying energy to the system when maintenance or adjustment is needed to the baler.
In EP 1 974 601, a similar auxiliary drive is foreseen which functions as a starting arrangement acting on the main drive of the baler and which is capable of acting as a sole drive of the baler or as a drive assisting the main drive in the first phase of the process of starting the baler. During the starting process, the main drive will accelerate to a higher speed than the auxiliary drive by means of a freewheel arrangement, whereupon the auxiliary drive ceases to have any effect on the remainder of the starting process. This auxiliary drive is used to overcome the problem that sometimes it is difficult to start up the baler and will assist by supplying energy to the baler during this start-up phase, after which it ceases to have any effect.
What is needed in the art is an agricultural baler which can start the flywheel at an initial start up state of the baler, regardless of the size of the traction unit powering the baler.